Question

4.   Ancient cyanobacteria released ______, which assisted in creating the atmosphere as we know it today.  

A. oxygen 
B. lead 
C. hydrogen 
D. ore 

A?

Reed told me yes for A,but I still was not sure!

Answer 1

I'm not Ms.Sue, but you're correct. :)

Answer 2

Thanks I will go with this answer and tell you if it was right.☺

Answer 3

The answer is a because Cyanobacteria are photosynthetic organisms, like plants, they produce sugars and O2 from carbon dioxide and water (..and energy from sunlight).

Answer 4

You were right.